And only Americans can decide from among their fellow citizens who that person will be.
It's not a new or revolutionary concept. They've been doing it for more than 200 years. It's what you do in a democracy - in a former colony that has had the gumption to let go of mummy's apron strings anyway.
Contrast that with the forelock pulling and jittery curtsies that will surround the leadership anointing process to be played out in New Zealand over the next week.
I say anointing, because unlike a proper democracy, we don't even have the chance to select, let alone elect, our head of state.
What we've got is our un-elected Queen of 60 years, at 86 too frail to make the royal progress through her far-flung Pacific dominions again, dispatching her eldest son as her deputy - and, in the goodness of time, her successor.
It's not even as if he's being sent out on "appro", like a home appliance the retailer lets you take home to try out before cash changes hands.
Monarchs are not like that. You can't look them over and say, "nah, we want topless Kate and Prince Whatsisname instead".
Nope, Prince Charles is our leader-to-be, like it or not.
Well that's not totally correct. It's true only as long as we go along with the feudal fancy that our head of state has to be the head of the reigning English royal house.
Plenty of old British colonies have ditched the British royals and moved on, retaining amicable relations with the old motherland. Places like India, Pakistan and much of southern Africa. Not forgetting the United States, though they did have to fight a war to achieve independence, unlike ourselves.
The royals themselves have given enough hints over the years that it's up to us to decide when to pension them off, and that when that happens, they'll go quietly.
Unfortunately, the published itinerary for the visit doesn't show any time set aside for a heart-to-heart with Prime Minister John Key along those lines. Instead there's the usual official chores at war memorials and hospitals and trade exhibitions, as well as an 11am performance of Hairy Maclary "with hundreds of schoolchildren at Bruce Mason Theatre, Takapuna".
In Auckland at Monday lunchtime, there's a public walkabout, through the debatable pleasures of the Lower Queen St bus terminus down to The Cloud on Queens Wharf for "New Zealand Shear Brilliance".
It's day-to-day drudgery, which almost makes me sorry for them. They seem as trapped in this meaningless relationship as we, and don't know how to get out of it either. Perhaps the United Nations should provide a counselling service for dragging feudal relationships into the 21st century.
Prince Charles does have a reputation in Britain for pushing the constitutional boundaries and expressing "political" views. If he sees no future in becoming the future King of New Zealand, I just wish he'd find time to let the Government know.
We've dithered so long, it would be churlish to dump the present Queen. But we do have to have an understanding in place with the palace that the monarchy of New Zealand expires with her. It's the natural cut-off point. For Charles, it can only be good. No more Hairy Maclary to endure.
